Mean equatorial gravity derived from various geopotential models

Summary Mean equatorial gravity has been computed from geopotential models GEM-10C, GEM-7, GEM-T1, GEM-T2, GEM-T3, JGM-1, JGM-2, JGM-3 and OSU91A and compared to the normal equatorial gravity, _e=978 032·699 × 10^–5 m s^–2, computed from four given parameters defining the Earth's level ellipsoid. In all models g_e>_e.     

Seismic hazard maps for the U.K.

Past studies of seismic hazard in the U.K. that have used modern probabilistic methods of hazard assessment have been site-specific studies, mostly in connection with nuclear installations. There has been a need for general-purpose maps of seismic hazard to show relative variation of exposure within the U.K. and to give some guidance on absolute values. Such maps have now been produced, incorporating, for the first time, the wealth of new information on historical earthquakes in Britain that has been gathered over the last 15 years. The hazard calculations were undertaken using a new computer code based on the USGS program SEISRISK III, but incorporating a logic tree approach to model variation in the input parameters (e.g. focal depth) or uncertainty in the formulation of the model (e.g. attenuation parameters). An innovative approach was taken to the formulation of seismic source zones, in which two overlapping models were employed. The first of these uses relatively broad source zones based loosely on an interpretation of seismicity and tectonics, while the second uses numerous small zones that reflect the locations of past significant earthquakes. This double approach (using the logic tree methodology) has the merit of both considering the general trend of earthquake activity as well as focusing in on known danger spots. The results show that the areas of highest hazard are western Scotland, north-western England and Wales, where the intensity with 90% probability of non-exceedance in 50 years is 6 EMS.     

转型发展期“多规合一”理论认知与技术方法

中国工业化、城镇化已进入转型发展新阶段,创新驱动发展与体制机制约束的矛盾加剧,资源短缺性及其配置低效性日益凸显,“多规合一”受到各级政府和学术界的广泛关注。推进“多规合一”,创新区域规划理论与技术方法,构建中国特色的国土空间规划体系成为当前全面深化改革的重要议题之一。本文深入分析了中国“多规不一”现实问题,总结了“多规”矛盾的本质特征,探讨了“多规合一”的战略定位,构建了“三主三分”的“多规合一”基本理论框架,提出了“三步走”多规逐步调适的技术途径及其长效机制。“多规合一”的核心在于从区域空间优化的战略高度统筹协调各项规划,科学引导城乡土地优化配置,实现“多规”在空间上的同一性、在功能上的融合性、在发展过程中的协同性。“多规合一”的重点是推进形成一个总分有序、层级清晰、职能精准的区域规划体系。     

切片采样算法在光释光年龄模型参数估计中的应用

光释光(OSL)年代学模型是基于数理统计学的一类概率密度模型,它根据特定的假设条件对样品等效剂量(De)分布进行数学解释,由此估计具有不同沉积历史或者能够代表样品实际埋藏年龄的De组分。年龄模型参数估计常通过极大似然估计(MLE)算法实现,本文尝试了切片采样算法在年龄模型参数优化中的应用。切片采样属于一种马尔科夫链蒙特卡罗采样(MCMC)算法,能根据测量数据与模型的联合似然函数进行随机采样,由此获得参数的采样分布。本文编写了实现年龄模型切片采样算法的应用程序,并使用模拟及实测De数据验证了该算法估计的可靠性。相对于MLE算法,MCMC算法具有对参数初值依赖性低、误差估计更准确的特点,切片采样算法提供了实现释光年龄模型参数估计的一种新方法。     

森林景观模型研究新进展及其应用

森林景观模型(forest landscape models)是基于森林动态机制和干扰作用在景观尺度上模拟和预测森林时空变化特征的计算机模型。该类模型越来越多地用于森林规划、经营管理、生态资源保护与恢复及全球气候变化研究。本文通过对大量文献资料的整理,对森林景观模型的概念、尺度、类型、方法、应用和最新研究进展进行了综述。随着计算机、地理信息系统、遥感等技术的迅猛发展,森林景观模型将会越来越多地与地理信息系统、规划经营管理决策等紧密结合,未来将向服务性决策模型方向发展。     

SIMS测定玻璃固化样品中铀分布的分析方法研究

玻璃固化是一种常用的高放废液固化方法,其优点在于具有较高的抗化学介质侵蚀的能力和很好的辐照稳定性、热稳定性和机械稳定性,其不足之处在于抗水浸出等性能有所下降而使其安全性需要进一步通过抗浸出实验来进行衡量和确认。使用二次离子质谱(SIMS)分析玻璃固化体中的放射性成分(如铀元素)的分布及浸出行为等各项指标,是一种评估玻璃固化体抗浸出性能的分析手段。本文应用SIMS测试模拟玻璃固化体,以碳作为镀膜材料通过真空蒸发镀碳的方法优化样品制备条件,有效地解决了样品导电性差的问题,~(235)U/~(238)U同位素测定结果约为7.9‰±0.395‰,基本符合制作模拟样品时所使用的天然铀的同位素特征(~(235)U/~(238)U参考值约7.3‰)。研究表明,建立的方法实现了铀元素同位素丰度的测量,能直接显示铀的分布情况,该方法可为研究玻璃固化体中放射性元素的浸出行为提供一定的技术支持。     

Integrating agriculture and energy to assess GHG emissions reduction: a methodological approach

Agriculture is responsible for approximately 25% of anthropogenic global GHG emissions. This significant share highlights the fundamental importance of the agricultural sector in the global GHG emissions reduction challenge. This article develops and tests a methodology for the integration of agricultural and energy systems modelling. The goal of the research is to extend an energy systems modelling approach to agriculture in order to provide richer insights into the dynamics and interactions between the two (e.g. in competition for land-use). We build Agri-TIMES, an agricultural systems module using the TIMES energy systems modelling framework, to model the effect of livestock emissions and explore emissions reduction options. The research focuses on Ireland, which is an interesting test case for two reasons: first, agriculture currently accounts for about 30% of Ireland's GHG emissions, significantly higher than other industrialized countries yet comparable with global levels (here including emissions associated with other land-use change and forestation); second, Ireland is both a complete and reasonably sized agricultural system to act as a test case for this new approach. This article describes the methodology used, the data requirements, and technical assumptions made to facilitate the modelling. It also presents results to illustrate the approach and provide associated initial insights.

Policy relevance

Most of the policy focus with regard to climate mitigation targets has been on reducing energy-related CO₂ emissions, which is understandable as they represent by far the largest source of emissions. Non-energy-related GHG emissions – largely from agriculture, industrial processes, and waste – have received significantly less attention in policy discourse. Going forward, however, if significant cuts are made in energy-related CO₂ emissions, the role of non-energy-related GHG emissions will grow in importance. It is therefore crucial that climate mitigation analyses and strategies are not limited to the energy system. This article shows the value of using integrated energy and agriculture techno-economic modelling techniques to draw evidence for new comprehensive climate policy strategies able to discern between the full range of technical solutions available. It enables the production of economy-wide least-cost climate mitigation pathways.     

基于地理国情普查数据的空间规划底图编制研究

空间规划底图编制是创新性地编制好市县经济社会发展总体规划、实施主体功能区制度、推动市县"多规合一"的重要基础。本文基于地理国情普查数据,开展空间规划底图编制生产性实验,对生产及技术环节提出指导意见,分析相关问题产生的原因,总结经验。     

Fitting boxes to Manhattan scenes using linear integer programming

We propose an approach for automatic generation of building models by assembling a set of boxes using a Manhattan-world assumption. The method first aligns the point cloud with a per-building local coordinate system, and then fits axis-aligned planes to the point cloud through an iterative regularization process. The refined planes partition the space of the data into a series of compact cubic cells (candidate boxes) spanning the entire 3D space of the input data. We then choose to approximate the target building by the assembly of a subset of these candidate boxes using a binary linear programming formulation. The objective function is designed to maximize the point cloud coverage and the compactness of the final model. Finally, all selected boxes are merged into a lightweight polygonal mesh model, which is suitable for interactive visualization of large scale urban scenes. Experimental results and a comparison with state-of-the-art methods demonstrate the effectiveness of the proposed framework.     

基于数据立方体的多最小支持度关联规则在犯罪分析中的应用

为了快速获取候选项集的支持度,避免频繁访问数据库而造成效率低下的问题,在MSapriori算法的基础上引入数据立方体,提出DC_MSapriori算法。该算法无需多次扫描事务数据库,减少了I/O操作,降低了搜索开销。实验基于福州市鼓楼区各大医院周边的案事件数据,快速挖掘出犯罪时空模式,验证了算法的有效性。